cgroup: honour sticky bit when trimming cgroup trees

[elogind.git] / src / cgroup-util.c

diff --git a/src/cgroup-util.c b/src/cgroup-util.c
index bbadc789a1651a30a2d995c85f807c704dc41b84..ec48ea63b4d0db188c7ba247953d64f0cfa20b88 100644 (file)
--- a/src/cgroup-util.c
+++ b/src/cgroup-util.c
@@ -153,17 +153,38 @@ int cg_read_subgroup(DIR *d, char **fn) {
         return 0;
 }
 
-int cg_rmdir(const char *controller, const char *path) {
+int cg_rmdir(const char *controller, const char *path, bool honour_sticky) {
         char *p;
         int r;
 
-        if ((r = cg_get_path(controller, path, NULL, &p)) < 0)
+        r = cg_get_path(controller, path, NULL, &p);
+        if (r < 0)
                 return r;
 
+        if (honour_sticky) {
+                char *tasks;
+
+                /* If the sticky bit is set don't remove the directory */
+
+                tasks = strappend(p, "/tasks");
+                if (!tasks) {
+                        free(p);
+                        return -ENOMEM;
+                }
+
+                r = file_is_sticky(tasks);
+                free(tasks);
+
+                if (r > 0) {
+                        free(p);
+                        return 0;
+                }
+        }
+
         r = rmdir(p);
         free(p);
 
-        return r < 0 ? -errno : 0;
+        return (r < 0 && errno != ENOENT) ? -errno : 0;
 }
 
 int cg_kill(const char *controller, const char *path, int sig, bool sigcont, bool ignore_self, Set *s) {
@@ -302,7 +323,7 @@ int cg_kill_recursive(const char *controller, const char *path, int sig, bool si
                 ret = r;
 
         if (rem)
-                if ((r = cg_rmdir(controller, path)) < 0) {
+                if ((r = cg_rmdir(controller, path, true)) < 0) {
                         if (ret >= 0 &&
                             r != -ENOENT &&
                             r != -EBUSY)
@@ -466,7 +487,7 @@ int cg_migrate_recursive(const char *controller, const char *from, const char *t
                 ret = r;
 
         if (rem)
-                if ((r = cg_rmdir(controller, from)) < 0) {
+                if ((r = cg_rmdir(controller, from, true)) < 0) {
                         if (ret >= 0 &&
                             r != -ENOENT &&
                             r != -EBUSY)
@@ -482,12 +503,26 @@ finish:
 
 int cg_get_path(const char *controller, const char *path, const char *suffix, char **fs) {
         const char *p;
-        char *mp;
-        int r;
+        char *t;
+        static __thread bool good = false;
 
         assert(controller);
         assert(fs);
 
+        if (_unlikely_(!good)) {
+                int r;
+
+                r = path_is_mount_point("/sys/fs/cgroup");
+                if (r <= 0)
+                        return r < 0 ? r : -ENOENT;
+
+                /* Cache this to save a few stat()s */
+                good = true;
+        }
+
+        if (isempty(controller))
+                return -EINVAL;
+
         /* This is a very minimal lookup from controller names to
          * paths. Since we have mounted most hierarchies ourselves
          * should be kinda safe, but eventually we might want to
@@ -501,29 +536,22 @@ int cg_get_path(const char *controller, const char *path, const char *suffix, ch
         else
                 p = controller;
 
-        if (asprintf(&mp, "/sys/fs/cgroup/%s", p) < 0)
-                return -ENOMEM;
-
-        if ((r = path_is_mount_point(mp)) <= 0) {
-                free(mp);
-                return r < 0 ? r : -ENOENT;
-        }
-
         if (path && suffix)
-                r = asprintf(fs, "%s/%s/%s", mp, path, suffix);
+                t = join("/sys/fs/cgroup/", p, "/", path, "/", suffix, NULL);
         else if (path)
-                r = asprintf(fs, "%s/%s", mp, path);
+                t = join("/sys/fs/cgroup/", p, "/", path, NULL);
         else if (suffix)
-                r = asprintf(fs, "%s/%s", mp, suffix);
-        else {
-                path_kill_slashes(mp);
-                *fs = mp;
-                return 0;
-        }
+                t = join("/sys/fs/cgroup/", p, "/", suffix, NULL);
+        else
+                t = join("/sys/fs/cgroup/", p, NULL);
 
-        free(mp);
-        path_kill_slashes(*fs);
-        return r < 0 ? -ENOMEM : 0;
+        if (!t)
+                return -ENOMEM;
+
+        path_kill_slashes(t);
+
+        *fs = t;
+        return 0;
 }
 
 int cg_trim(const char *controller, const char *path, bool delete_root) {
@@ -536,7 +564,7 @@ int cg_trim(const char *controller, const char *path, bool delete_root) {
         if ((r = cg_get_path(controller, path, NULL, &fs)) < 0)
                 return r;
 
-        r = rm_rf(fs, true, delete_root);
+        r = rm_rf(fs, true, delete_root, true);
         free(fs);
 
         return r == -ENOENT ? 0 : r;